Apparatus for nonwoven fabric manufacture

ABSTRACT

Apparatus for making of nonwoven fabrics formed of strands which are bonded to each other at selected locations concomitantly with the extrusion thereof.

United States Patent Theodore H. Fairbanks West Chester, Pa. 695,007

Jan. 2, 1968 Sept. 2 1, 1971 FMC Corp. Philadelphia, Pa.

[72] Inventor [21 Appl. No. [22] Filed [45] Patented [73] Assignee [54] APPARATUS FOR NONWOVEN FABRIC MANUFACTURE 4 Claims, 3 Drawing Figs.

[52] U.S.Cl 156/441, 156/166, 156/181, 156/500 [51] int. Cl D04h 3/02 [50] Field 01 Search 156/167, 180, 181, 296, 306, 166, 290,441, 209, 500

[56] References Cited UNITED STATES PATENTS 3,481,818 12/1969 Wellen 156/500 3,327,708 6/ 1967 Sok olowski 156/290 3,221,738 12/1965 Ekberg et al 156/290 2,207,279 7/1940 Alderfer 156/181 2,493,968 1/1950 Hepner.... 156/290 2,621,139 12/1952 Messing... 156/290 2,760,881 8/1956 Tou1min.. 156/209 2,938,821 5/1960 Nack 156/167 3,255,064 6/1966 Makansi..... 156/209 3,308,220 3/1967 Smith 156/441 3,311,519 3/1967 Touey et al. 156/180 3,393,110 7/1968 Slade 156/290 3,436,304 4/ 1969 Spence 156/167 3,439,085 4/1969 Hartmann 156/167 Primary ExaminerCar1 D. Quarforth Assistant ExaminerBrooks H. Hunt Altorneys-Thomas R. OMalley, George F. Mueller and Eugene G. Horsky ABSTRACT: Apparatus for making of nonwoven fabrics formed of strands which are bonded to each other at selected locations concomitantly with the extrusion thereof.

APPARATUS FOR NONWOVEN FABRIC MANUFACTURE The present invention relates to an improved apparatus for making nonwoven fabrics.

Nonwoven fabrics have long been made using preformed fibers, for example, by disposing the same into a batt or layer and then bonding the fibers to each other at spaced areas. It has heretofore been recognized that procedures for making nonwoven fabrics which involve manipulation and treatment of preformed fibers are not only costly but often involve some damage to the fibers themselves. Thus, various proposals have been made for making nonwoven fabrics by extrusion, as by depositing extruded streams of strand-forming material along intersecting or crossing paths.

The proposed procedures for making nonwoven fabrics by extrusion, however, have not been widely accepted. Too often, the extrusion procedures involve low rates of production and thus are economically unfeasible. In other instances, the nonwoven fabrics which are produced lack covering power and/or uniformity and/or desirable stiffness or flexibility along certain of its directions. Accordingly, a primary object of this invention is to provide an improved and more satisfactory apparatus for making nonwoven fabrics.

Another object of this invention is to provide an improved apparatus for making nonwoven fabrics from continuous strands concomitantly with the extrusion thereof.

Still another object is the provision of an apparatus for making, at high production rates, a nonwoven fabric having good covering power and stiffness characteristics, yet which is desirably porous.

A further object is the provision of an apparatus for making nonwoven fabrics from extruded continuous strands which are strongly bonded to each other at selected areas.

A still further object is the provision of an apparatus for making nonwoven fabrics which are free of unattached or loose fibers.

These and other objects are accomplished in accordance with the present invention by an apparatus in which a series of generally parallel streams of flowable strand-forming material is continuously extruded in each of a plurality of overlying planes and, concomitantly with the extrusion, streams in each series are bonded with streams in the other series at longitudinally spaced intervals thereof. Preferably, each of these areas at which the streams are bonded extends only partially across the planes of extrusion and is in staggered and overlapping relationship with adjacent of such areas. Thus, a number of such adjacent, staggered areas, when taken together, effect a bonding of the streams entirely across the planes of extrusion. After the desired bonding of streams has been achieved, the streams are set to provide a unitary or integral nonwoven fabric.

The above planes along which the series of streams are extruded are preferably parallel with each other and the streams in each of the series are staggered or offset from the streams in at least the adjacent and preferably all of the other of such series of streams. Thus, as the streams in the series of streams are bonded to each other at spaced areas,- as by pressing or squeezing the same together, rather than overlying each other, the streams of each series of streams occupy spaces between streams of the other of such series and, in effect, mesh with each other.

The areas of bonding of the different series of streams preferably extend transversely of and either partially or entirely across the planes of extrusion. Bonding of the streams along areas which extend partially, rather than completely, across the planes of extrusion is preferred since the resulting fabric has a greater degree of flexibility in its longitudinal direction. In accordance with this preferred procedure, each of such areas of bonding overlap or extend beyond the ends of ad jacent of such bonded areas with which they are in staggered relationship. During the bonding of the streams, as described above, there is no disruption in the extrusion of the streams of strand-forming material or any weakening of such streams at the areas of bonding.

Although a partial setting up of the streams prior to bonding may not be harmful, it is still essential that the streams be bonded to each other while they are still in a plastic or tacky condition and thus the bonding of streams is effected as soon as is possible after their extrusion. Setting of the extruded and bonded streams of flowable strand-forming material to provide a unitary nonwoven fabric is achieved in a conventional manner, as by cooling, solvent removal or chemical conversion, depending upon the particular character of the strandforming material which is employed.

The apparatus of the present invention includes, in general, a means for extruding a series of generally parallel streams of strand-forming material in each of a plurality of overlying planes, means for setting such extruded streams, and means located between the extrusion and setting means for pressing or squeezing streams in each series of extruded streams into contact with streams of the other of such series of streams at longitudinally spaced intervals thereof. Preferably, the areas at which the streams are pressed together extend only partially across the planes ofextrusion and are in staggered relationship with adjacent of such areas.

Satisfactory combining of the streams at desired areas includes rollers which extend across the planes of extrusion along opposite sides thereof. Each of such rollers is provided with rows of projections which are generally parallel to the roller axis and are spaced annularly about its periphery. The projections in each row extend only partially across the roller length and are in staggered relationship with at least the projections in the rows which are adjacent thereto. These rollers are both turned at the same rate of speed in the direction of extrusion and the projections are arranged thereon so as to mate with each other as they engage with the streams of strand-forming material travelling therebetween.

The teachings of the present invention are applicable for use with a variety of materials, which are referred to by the terms strand-forming or plastic," including materials which are thermoplastic, such as polyamides or superpolyamides, polyesters, polyvinyl chloride, copolymers thereof, polyolefms, cellulose acetates, metals, glasses, etc., natural or synthetic rubbers, therrnosetting materials or wet-spinnable materials, such as viscose, cupro-ammonium cellulose, or carboxymethyl cellulose. Such materials may include various additives such as stabilizers, dyes, foaming agents, etc., if so desired.

For a greater understanding of this invention, reference is made to the following detailed description and drawing in which FIG. 1 is a side view of an apparatus of the present invention;

FIG. 2 is a front view of the apparatus shown in FIG. 1; and

FIG. 3 is a perspective view of a portion ofa nonwoven fabric formed by the apparatus shown in FIGS. 1 and 2.

With reference to the drawing apparatus 11, having rows of extrusion openings, is provided for continuously extruding a series of generally parallel streams 13 of strand-forming material in each of a plurality of overlying and preferably parallel planes, as indicated at 15, 17, 19, 21, 23 and 25 in FIG. 1. The extruded streams 13 consisting, for example, of thermoplastic polymeric material, are set with a cool gas, such as air, which is delivered by nozzles 27, which are located below the extrusion apparatus 11 and along opposite sides of the planes of extrusion.

Between the extrusion apparatus 11 and nozzles are positioned rollers 29 and 31 each having a shaft 33 which projects beyond the ends of the respective roller and is supported by an appropriate frame. Suitable drive means, not shown, is provided for rotating the rollers 29 and 31 at substantially the same rate of speed in the direction as indicated by arrows 35 and 37, respectively.

The rollers 29 and 31 are of like construction, each having projections 39 which are disposed in rows extending substantially parallel to the roller axis and spaced annularly about the roller periphery. In the preferred construction shown in FIG. 2, each projection 39 extends only along a portion of the length of the respective rollers. Further, it will be noted that the projections 39 in adjacent rows are in staggered or offset and overlapping relationship. That is, a projection 39 in one row extends beyond the ends of the projections 39 in adjacent rows with which it is in staggered relationship.

In the operation of the described apparatus, the rollers 29 and 31 are rotated in the direction of arrows 35 and 37 and a series of generally parallel streams 13 of thermoplastic material is extruded from the apparatus 11 in each of the overlying planes l5, l7, 19, 21, 23 and 25. During their passage between the rotating rollers 29 and 31, the series of streams are pressed or squeezed together at spaced areas by the cooperating roller projections 39.

Preferably, the extrusion openings in each such row of openings in the apparatus 11 are offset or staggered relative to at least the openings in rows which are adjacent thereto so that the extruded streams 13 of each series of streams are also offset or staggered with relation to streams in the other of such series of streams. Thus, as such streams are pressed or squeezed together by the roller projections, streams of thermoplastic material of each series of streams occupy the spaces between the other of such series of streams rather than being bunched and overlying with each other. The spacing of the streams of the different series must be such as to insure that the streams make contact with each other when pressed or squeezed together by the roller projections.

Once past the rollers 29 and 31, the now bonded streams of thermoplastic material are set, as by cool air discharged from nozzles 27, to provide a unitary or integral nonwoven fabric 41, as shown in FIG. 3. In the finished fabric 41, the areas at which bonding has occurred are indicated at 43 and it will be noted that the areas 43 are in staggered and overlapping relationship. While the bonded areas 43 are, of course, of reduced thickness, the unbonded portions of the strands impart bulk to the fabric 41 and give it a quiltlike appearance. If desired, the nonwoven fabric 41 may be longitudinally stretched to orient the molecules thereof and thus improve its strength characteristics.

While the areas of bonding 43 in the finished nonwoven fabric 41 have been described and illustrated as being substantially straight and extending along planes which are perpendicular to the planes of extrusion, the shape of such areas 43, as well as their angular relationship to the strands may be varied without departing from the teachings of the invention.

It is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. Apparatus for making a nonwoven fabric including means having rows of extrusion openings which are arranged to extrude a series of spaced streams of flowable strand-forming material in each of a plurality of overlying, substantially parallel planes with the streams of each series of streams being generally parallel to each other and to the streams in the other of such series, the openings in each such row of openings being in staggered relationship with at least the openings in rows which are adjacent thereto, means spaced from said extrusion means for setting the extruded streams of strand-forming material, and means positioned between said extrusion and setting means and having cooperating projections for pressing streams in each series of streams into contact with streams of other of such series only at longitudinally spaced intervals thereof along areas which extend at least partially across the planes of extrusion.

2. Apparatus as defined in claim 1 wherein said pressing means includes a pair of rollers which extend across the planes of extrusion and between which the streams are extruded, said rollers each having rows of said projections spaced annularly along the periphery thereof, the projections in each row of projections each being shorter than the roller length and disposed in staggered relationship with at least the projections in adjacent of such rows, and means for together rotating said rollers.

3. Apparatus as defined in claim 2 wherein the rows of roller projections extend substantially parallel to the roller axis and the projection of the two rollers mate with each other.

4. Apparatus as defined in claim 2 wherein at least one end of each roller projection extends beyond the adjacent end of a roller projection with which it is in staggered relationship whereby such staggered projections overlap each other. 

2. Apparatus as defined in claim 1 wherein said pressing means includes a pair of rollers which extend across the planes of extrusion and between which the streams are extruded, said rollers each having rows of said projections spaced annularly along the periphery thereof, the projections in each row of projections each being shorter than the roller length and disposed in staggered relationship with at least the projections in adjacent of such rows, and means for together rotating said rollers.
 3. Apparatus as defined in claim 2 wherein the rows of roller projections extend substantially parallel to the roller axis and the projection of the two rollers mate with each other.
 4. Apparatus as defined in claim 2 wherein at least one end of each roller projection extends beyond the adjacent end of a roller projection with which it is in staggered relationship whereby such staggered projections overlap each other. 